[RFC PATCH 09/11] rust: add basic PCI driver abstractions
From: Danilo Krummrich
Date: Mon May 20 2024 - 13:30:21 EST
From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
This commit implements the abstractions necessary to bind a most basic
PCI driver to a PCI device. It also serves as a ground layer for further
PCI functionality.
Specifically, a basic PCI driver has to provide register() and
unregister() methods, a PCI device structure for Rust, and probe() and
remove() callbacks for the C side.
A PCI driver shall be able to register itself for the desired devices,
recognized by their device ID. Another basic necessity is the ability to
store driver data, i.e., through pci_set_drvdata().
In congruency with the C implementation of pci_dev, a Rust PCI device
holds a basic device (device::Device) which is always reference counted
to ensure it cannot disappear as long as there are still users.
Holding a basic device allows for both using interfaces that require a
device, as well as such that demand a pci_dev, which can be obtained
through as_raw(), using the established container_of() macro.
Implement a basic driver model with probe() and remove() callbacks,
implementing the corresponding traits from the 'driver' crate.
Implement PCI device IDs.
Implement pci::Device with basic methods, holding an always reference
counted device::Device.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
Co-developed-by: Philipp Stanner <pstanner@xxxxxxxxxx>
Signed-off-by: Philipp Stanner <pstanner@xxxxxxxxxx>
Co-developed-by: Danilo Krummrich <dakr@xxxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
rust/bindings/bindings_helper.h | 1 +
rust/helpers.c | 18 ++
rust/kernel/lib.rs | 2 +
rust/kernel/pci.rs | 328 ++++++++++++++++++++++++++++++++
4 files changed, 349 insertions(+)
create mode 100644 rust/kernel/pci.rs
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ddb5644d4fd9..32221de16e57 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -11,6 +11,7 @@
#include <linux/ethtool.h>
#include <linux/jiffies.h>
#include <linux/mdio.h>
+#include <linux/pci.h>
#include <linux/phy.h>
#include <linux/refcount.h>
#include <linux/sched.h>
diff --git a/rust/helpers.c b/rust/helpers.c
index 34061eca05a0..c3d80301185c 100644
--- a/rust/helpers.c
+++ b/rust/helpers.c
@@ -33,6 +33,7 @@
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
+#include <linux/pci.h>
__noreturn void rust_helper_BUG(void)
{
@@ -178,6 +179,23 @@ int rust_helper_devm_add_action(struct device *dev, void (*action)(void *), void
return devm_add_action(dev, action, data);
}
+void rust_helper_pci_set_drvdata(struct pci_dev *pdev, void *data)
+{
+ pci_set_drvdata(pdev, data);
+}
+EXPORT_SYMBOL_GPL(rust_helper_pci_set_drvdata);
+
+void *rust_helper_pci_get_drvdata(struct pci_dev *pdev)
+{
+ return pci_get_drvdata(pdev);
+}
+EXPORT_SYMBOL_GPL(rust_helper_pci_get_drvdata);
+
+u64 rust_helper_pci_resource_len(struct pci_dev *pdev, int barnr)
+{
+ return pci_resource_len(pdev, barnr);
+}
+
/*
* `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
* use it in contexts where Rust expects a `usize` like slice (array) indices.
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 11645060b444..606391cbff83 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -55,6 +55,8 @@
#[doc(hidden)]
pub use bindings;
pub use macros;
+#[cfg(all(CONFIG_PCI, CONFIG_PCI_MSI))]
+pub mod pci;
pub use uapi;
#[doc(hidden)]
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
new file mode 100644
index 000000000000..323aea565d84
--- /dev/null
+++ b/rust/kernel/pci.rs
@@ -0,0 +1,328 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Wrappers for the PCI subsystem
+//!
+//! C header: [`include/linux/pci.h`](../../../../include/linux/pci.h)
+
+use crate::{
+ bindings, container_of, device, driver,
+ error::{to_result, Result},
+ str::CStr,
+ types::{ARef, ForeignOwnable},
+ ThisModule,
+};
+use kernel::prelude::*; // for pinned_drop
+
+/// An adapter for the registration of PCI drivers.
+///
+/// # Example
+///
+///```
+/// use kernel::pci;
+///
+/// impl pci::Driver for MyDriver {
+/// type Data = Arc<MyDeviceData>;
+///
+/// define_pci_id_table! {
+/// (),
+/// [ (pci::DeviceId::new(bindings::PCI_VENDOR_ID_MY_VENDOR,
+/// bindings::PCI_ANY_ID as u32),
+/// None)
+/// ]
+/// }
+///
+/// fn probe(
+/// pdev: &mut pci::Device,
+/// id_info: Option<&Self::IdInfo>
+/// ) -> Result<Arc<Self::Data>> {
+/// ...
+/// }
+///
+/// fn remove(data: &Self::Data) {
+/// ...
+/// }
+/// }
+///
+/// struct MyModule {
+/// _registration: Pin<Box<driver::Registration<pci::Adapter<MyDriver>>>>,
+/// }
+///
+/// impl kernel::Module for MyModule {
+/// fn init(_name: &'static CStr, module: &'static ThisModule) -> Result<Self> {
+/// let registration = driver::Registration::new_pinned(c_str!("MyDriver"), module)?;
+///
+/// Ok(Self {
+/// _registration: registration,
+/// })
+/// }
+/// }
+///```
+pub struct Adapter<T: Driver>(T);
+
+impl<T: Driver> driver::DriverOps for Adapter<T> {
+ type RegType = bindings::pci_driver;
+
+ // SAFETY: The caller must ensure that `reg` is valid and unequal NULL.
+ unsafe fn register(
+ reg: *mut bindings::pci_driver,
+ name: &'static CStr,
+ module: &'static ThisModule,
+ ) -> Result {
+ // SAFETY: Guaranteed by the safety requirements of this function.
+ let pdrv: &mut bindings::pci_driver = unsafe { &mut *reg };
+
+ pdrv.name = name.as_char_ptr();
+ pdrv.probe = Some(Self::probe_callback);
+ pdrv.remove = Some(Self::remove_callback);
+ pdrv.id_table = T::ID_TABLE.as_ref();
+ // SAFETY: Guaranteed by the safety requirements of this function.
+ to_result(unsafe { bindings::__pci_register_driver(reg, module.0, name.as_char_ptr()) })
+ }
+
+ // SAFETY: The caller must ensure that `reg` is valid and unequal NULL.
+ unsafe fn unregister(reg: *mut bindings::pci_driver) {
+ // SAFETY: Guaranteed by the safety requirements of this function.
+ unsafe { bindings::pci_unregister_driver(reg) }
+ }
+}
+
+impl<T: Driver> Adapter<T> {
+ extern "C" fn probe_callback(
+ pdev: *mut bindings::pci_dev,
+ id: *const bindings::pci_device_id,
+ ) -> core::ffi::c_int {
+ // SAFETY: Safe because the core kernel only ever calls the probe callback with a valid
+ // `pdev`.
+ let dev = unsafe { device::Device::from_raw(&mut (*pdev).dev) };
+ // SAFETY: Guaranteed by the rules described above.
+ let mut pdev = unsafe { Device::from_dev(dev) };
+
+ // SAFETY: `id` is a pointer within the static table, so it's always valid.
+ let offset = unsafe { (*id).driver_data };
+ let info = {
+ // SAFETY: The offset comes from a previous call to `offset_from` in `IdArray::new`,
+ // which guarantees that the resulting pointer is within the table.
+ let ptr = unsafe {
+ id.cast::<u8>()
+ .offset(offset as _)
+ .cast::<Option<T::IdInfo>>()
+ };
+ // SAFETY: Guaranteed by the preceding safety requirement.
+ unsafe { (*ptr).as_ref() }
+ };
+ match T::probe(&mut pdev, info) {
+ Ok(data) => {
+ // SAFETY:
+ // A valid `pdev` is always passed to this function. `data` is always valid since
+ // it's created in Rust.
+ unsafe { bindings::pci_set_drvdata(pdev.as_raw(), data.into_foreign() as _) };
+ }
+ Err(err) => return Error::to_errno(err),
+ }
+
+ 0
+ }
+
+ extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {
+ // SAFETY: This function is called by the C side and always with a valid `pdev`.
+ let ptr = unsafe { bindings::pci_get_drvdata(pdev) };
+ // SAFETY: Guaranteed by the preceding safety requirement.
+ let data = unsafe { T::Data::from_foreign(ptr) };
+ T::remove(&data);
+ <T::Data as driver::DeviceRemoval>::device_remove(&data);
+ }
+}
+
+/// Abstraction for bindings::pci_device_id.
+#[derive(Clone, Copy)]
+pub struct DeviceId {
+ /// Vendor ID
+ pub vendor: u32,
+ /// Device ID
+ pub device: u32,
+ /// Subsystem vendor ID
+ pub subvendor: u32,
+ /// Subsystem device ID
+ pub subdevice: u32,
+ /// Device class and subclass
+ pub class: u32,
+ /// Limit which sub-fields of the class
+ pub class_mask: u32,
+}
+
+impl DeviceId {
+ const PCI_ANY_ID: u32 = !0;
+
+ /// PCI_DEVICE macro.
+ pub const fn new(vendor: u32, device: u32) -> Self {
+ Self {
+ vendor,
+ device,
+ subvendor: DeviceId::PCI_ANY_ID,
+ subdevice: DeviceId::PCI_ANY_ID,
+ class: 0,
+ class_mask: 0,
+ }
+ }
+
+ /// PCI_DEVICE_CLASS macro.
+ pub const fn with_class(class: u32, class_mask: u32) -> Self {
+ Self {
+ vendor: DeviceId::PCI_ANY_ID,
+ device: DeviceId::PCI_ANY_ID,
+ subvendor: DeviceId::PCI_ANY_ID,
+ subdevice: DeviceId::PCI_ANY_ID,
+ class,
+ class_mask,
+ }
+ }
+
+ /// PCI_DEVICE_ID macro.
+ pub const fn to_rawid(&self, offset: isize) -> bindings::pci_device_id {
+ bindings::pci_device_id {
+ vendor: self.vendor,
+ device: self.device,
+ subvendor: self.subvendor,
+ subdevice: self.subdevice,
+ class: self.class,
+ class_mask: self.class_mask,
+ driver_data: offset as _,
+ override_only: 0,
+ }
+ }
+}
+
+// SAFETY: `ZERO` is all zeroed-out and `to_rawid` stores `offset` in `pci_device_id::driver_data`.
+unsafe impl driver::RawDeviceId for DeviceId {
+ type RawType = bindings::pci_device_id;
+
+ const ZERO: Self::RawType = bindings::pci_device_id {
+ vendor: 0,
+ device: 0,
+ subvendor: 0,
+ subdevice: 0,
+ class: 0,
+ class_mask: 0,
+ driver_data: 0,
+ override_only: 0,
+ };
+}
+
+/// Define a const pci device id table
+///
+/// # Examples
+///
+/// ```ignore
+/// # use kernel::{pci, define_pci_id_table};
+/// #
+/// struct MyDriver;
+/// impl pci::Driver for MyDriver {
+/// // [...]
+/// # fn probe(_dev: &mut pci::Device, _id_info: Option<&Self::IdInfo>) -> Result {
+/// # Ok(())
+/// # }
+/// # define_pci_id_table! {u32, [
+/// # (pci::DeviceId::new(0x010800, 0xffffff), None),
+/// # (pci::DeviceId::with_class(0x010802, 0xfffff), Some(0x10)),
+/// # ]}
+/// }
+/// ```
+#[macro_export]
+macro_rules! define_pci_id_table {
+ ($data_type:ty, $($t:tt)*) => {
+ type IdInfo = $data_type;
+ const ID_TABLE: $crate::driver::IdTable<'static, $crate::pci::DeviceId, $data_type> = {
+ $crate::define_id_array!(ARRAY, $crate::pci::DeviceId, $data_type, $($t)* );
+ ARRAY.as_table()
+ };
+ };
+}
+pub use define_pci_id_table;
+
+/// The PCI driver trait.
+///
+/// Drivers must implement this trait in order to get a PCI driver registered. Please refer to the
+/// `Adapter` documentation for an example.
+pub trait Driver {
+ /// Data stored on device by driver.
+ ///
+ /// Corresponds to the data set or retrieved via the kernel's
+ /// `pci_{set,get}_drvdata()` functions.
+ ///
+ /// Require that `Data` implements `ForeignOwnable`. We guarantee to
+ /// never move the underlying wrapped data structure.
+ ///
+ /// TODO: Use associated_type_defaults once stabilized:
+ ///
+ /// `type Data: ForeignOwnable + driver::DeviceRemoval = ();`
+ type Data: ForeignOwnable + driver::DeviceRemoval;
+
+ /// The type holding information about each device id supported by the driver.
+ ///
+ /// TODO: Use associated_type_defaults once stabilized:
+ ///
+ /// type IdInfo: 'static = ();
+ type IdInfo: 'static;
+
+ /// The table of device ids supported by the driver.
+ const ID_TABLE: driver::IdTable<'static, DeviceId, Self::IdInfo>;
+
+ /// PCI driver probe.
+ ///
+ /// Called when a new platform device is added or discovered.
+ /// Implementers should attempt to initialize the device here.
+ fn probe(dev: &mut Device, id: Option<&Self::IdInfo>) -> Result<Self::Data>;
+
+ /// PCI driver remove.
+ ///
+ /// Called when a platform device is removed.
+ /// Implementers should prepare the device for complete removal here.
+ fn remove(_data: &Self::Data);
+}
+
+/// The PCI device representation.
+///
+/// A PCI device is based on an always reference counted `device:Device` instance. Cloning a PCI
+/// device, hence, also increments the base device' reference count.
+#[derive(Clone)]
+pub struct Device(ARef<device::Device>);
+
+impl Device {
+ /// Create a PCI Device instance from an existing `device::Device`.
+ ///
+ /// # Safety
+ ///
+ /// `dev` must be an `ARef<device::Device>` whose underlying `bindings::device` is a member of
+ /// a `bindings::pci_dev`.
+ pub unsafe fn from_dev(dev: ARef<device::Device>) -> Self {
+ Self(dev)
+ }
+
+ fn as_raw(&self) -> *mut bindings::pci_dev {
+ // SAFETY: Guaranteed by the requirements described in pci::Device::new().
+ unsafe { container_of!(self.0.as_raw(), bindings::pci_dev, dev) as _ }
+ }
+
+ /// Enable the Device's memory.
+ pub fn enable_device_mem(&self) -> Result {
+ // SAFETY: By the type invariants, we know that `self.ptr` is non-null and valid.
+ let ret = unsafe { bindings::pci_enable_device_mem(self.as_raw()) };
+ if ret != 0 {
+ Err(Error::from_errno(ret))
+ } else {
+ Ok(())
+ }
+ }
+
+ /// Set the Device's master.
+ pub fn set_master(&self) {
+ // SAFETY: By the type invariants, we know that `self.ptr` is non-null and valid.
+ unsafe { bindings::pci_set_master(self.as_raw()) };
+ }
+}
+
+impl AsRef<device::Device> for Device {
+ fn as_ref(&self) -> &device::Device {
+ &self.0
+ }
+}
--
2.45.1